#include <iostream>

using namespace std;


// 定义一个命名空间
namespace spaceA{
	int g_a = 10;
}

namespace spaceB{
	int a = 20;
	namespace sapceC{
		struct teacher{
			int id;
			char name[64];
		};
	}
}


int main(int argc, char *argv[]) {

	using namespace spaceA;
	using spaceB::sapceC::teacher;

	// prints
	cout << spaceA::g_a << endl;
	cout << g_a << endl;

	struct teacher t;
	t.id = 12;
	cout << t.id << endl;

	return 0;
}
